1. Field of the Invention
This invention relates to an axial securing device and more particularly to a device for axially securing the shaft of a small motor wherein one end of the shaft is connected solidly with a rotor of the motor, the other end is supported by a thrust bearing of the stator and the securing element is snapped into an annular groove of the shaft for axially securing the shaft and which is located in a recess of the stator. According to the invention, the securing element and the recess have contact surfaces which cooperate when the shaft is inserted into the stator to shift the securing element, during radial elongation, onto the shaft and far enough in front of the annular groove to lock into the groove by itself as it continues its axial motion.
2. Description of the Prior Art
A fan with a small motor that has such an axial securing mechanism is known in the art from German Offenlegungsschrift 27 18 428 in which the axial securing mechanism prevents the rotor from falling out axially when running freely suspended. According to the reference, a snap ring is applied on the free end of the shaft and it lies against the inner ring of a ball bearing or, via an additional rotor disk, a friction bearing. An axial stress is exerted on the bearing by means of a spring supported on an additional snap ring. This axial securing means is very expensive to produce and the extent of axial play is not sufficiently precisely determinable. In addition, the service life of the motor is limited due to the unavoidable entry of impurities into the bearing and to the escape of lubricant.
Japanese Utility Model Patent No. 61-72076 (72076/1986) discloses a small motor, in which the axial securing of the shaft involves expensive permanent magnets and a cover protecting the bearing.
The present invention is addressed to an axial securing device, which is particularly suited for a small motor in a fan and which avoids the above shortcomings. Cost-effective production and assembly should also be possible in mass production and precise observance of a specified play should also be assured.